KDChartTextLabelCache.h

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/****************************************************************************
** Copyright (C) 2001-2020 Klaralvdalens Datakonsult AB.  All rights reserved.
**
** This file is part of the KD Chart library.
**
** Licensees holding valid commercial KD Chart licenses may use this file in
** accordance with the KD Chart Commercial License Agreement provided with
** the Software.
**
**
** This file may be distributed and/or modified under the terms of the
** GNU General Public License version 2 and version 3 as published by the
** Free Software Foundation and appearing in the file LICENSE.GPL.txt included.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
** Contact info@kdab.com if any conditions of this licensing are not
** clear to you.
**
**********************************************************************/

#ifndef KDCHARTTEXTLABELCACHE_H
#define KDCHARTTEXTLABELCACHE_H

#include <QPixmap>
#include <QFont>
#include <QBrush>
#include <QPen>

#include "KDChartEnums.h"

class PrerenderedElement {
public:
    PrerenderedElement();
    virtual ~PrerenderedElement() {}

    virtual const QPixmap& pixmap() const = 0;

    virtual QPointF referencePointLocation( KDChartEnums::PositionValue ) const = 0;

    void setPosition( const QPointF& position );
    const QPointF& position() const;

    void setReferencePoint( KDChartEnums::PositionValue );
    KDChartEnums::PositionValue referencePoint() const;

protected:
    virtual void invalidate() const = 0;

private:
    QPointF m_position;
    KDChartEnums::PositionValue m_referencePoint;
};

// FIXME this is merely a prototype
// FIXME caching could be done by a second layer that can be used to,
// e.g., query for a prerendered element by id or name, or by changing
// the pixmap() method to do lazy evaluation.
class PrerenderedLabel : public PrerenderedElement
{
public:
    PrerenderedLabel();
    ~PrerenderedLabel() override;

    void setFont( const QFont& font );
    const QFont& font() const;

    void setText( const QString& text );
    const QString& text() const;

    void setBrush( const QBrush& brush );
    const QBrush& brush() const;

    void setPen( const QPen& );
    const QPen& pen() const;

    void setAngle( qreal angle );
    qreal angle() const;

    // reimpl PrerenderedElement:
    const QPixmap& pixmap() const override;
    QPointF referencePointLocation( KDChartEnums::PositionValue position ) const override;
    // overload: return location of referencePoint():
    QPointF referencePointLocation() const;

protected:
    void invalidate() const override;

private:
    void paint() const;

    // store the settings (these are used for the painting):
    mutable bool m_dirty;
    QFont m_font;
    QString m_text;
    QBrush m_brush;
    QPen m_pen;
    qreal m_angle;

    // these are valid once the label has been rendered:
    mutable QPixmap m_pixmap;
    mutable QPointF m_referenceBottomLeft;
    mutable QPointF m_textBaseLineVector;
    mutable QPointF m_textAscendVector;
};

#endif